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datetime="2021-01-15T02:49:00.628Z" title="发表于 2021-01-15 10:49:00">2021-01-15</time><span class="post-meta-separator">|</span><i class="fas fa-history fa-fw post-meta-icon"></i><span class="post-meta-label">更新于</span><time class="post-meta-date-updated" datetime="2021-03-20T10:06:33.008Z" title="更新于 2021-03-20 18:06:33">2021-03-20</time></span><span class="post-meta-categories"><span class="post-meta-separator">|</span><i class="fas fa-inbox fa-fw post-meta-icon"></i><a class="post-meta-categories" href="/categories/%E8%AE%A1%E7%AE%97%E6%9C%BA%E5%9F%BA%E7%A1%80/">计算机基础</a><i class="fas fa-angle-right post-meta-separator"></i><i class="fas fa-inbox fa-fw post-meta-icon"></i><a class="post-meta-categories" href="/categories/%E8%AE%A1%E7%AE%97%E6%9C%BA%E5%9F%BA%E7%A1%80/C%E8%AF%AD%E8%A8%80%E7%A8%8B%E5%BA%8F%E8%AE%BE%E8%AE%A1/">C语言程序设计</a></span></div><div class="meta-secondline"><span class="post-meta-separator">|</span><span class="post-meta-wordcount"><i class="far fa-file-word fa-fw post-meta-icon"></i><span class="post-meta-label">字数总计:</span><span class="word-count">3.3k</span><span class="post-meta-separator">|</span><i class="far fa-clock fa-fw post-meta-icon"></i><span class="post-meta-label">阅读时长:</span><span>12分钟</span></span><span class="post-meta-separator">|</span><span class="post-meta-pv-cv" id="" data-flag-title="C语言⭐函数"><i class="far fa-eye fa-fw post-meta-icon"></i><span class="post-meta-label">阅读量:</span><span id="busuanzi_value_page_pv"></span></span></div></div></div><article class="post-content" id="article-container"><h1 id="函数"><a href="#函数" class="headerlink" title="函数"></a>函数</h1><ul>
<li>无参函数<pre><code>  类型名 函数名()
  &#123;
      //函数体包括声明部分和语句部分
  &#125;</code></pre>
</li>
<li>有参函数<pre><code>  类型名 函数名(形式参数列表)
  &#123;
      //函数体
  &#125;</code></pre>
<h2 id="虚实结合"><a href="#虚实结合" class="headerlink" title="虚实结合"></a>虚实结合</h2><pre><code>  int max(int x,int y); //x，y为形参
  int a=1,b=2,m;
  m=max(1,2);   //a,b为实参</code></pre>
形参并不占内存中的存储单元，当被调用时，临时分配内存单元。<br>实参向形参的数据传递是”值传递’，单向传递，形参不能传给实参，因为他们具有不同的存储单元。</li>
</ul>
<h2 id="返回值"><a href="#返回值" class="headerlink" title="返回值"></a>返回值</h2><p>函数的返回值是通过return语句获得的。<br>函数类型决定返回值的类型。</p>
<pre><code>    int max(int x,int y)
    &#123;
    return(x&gt;y?x:y);
    &#125;</code></pre>
<p>对于不带返回值，可以定义函数为void，定义后不允许出现return语句。</p>
<h2 id="函数声明"><a href="#函数声明" class="headerlink" title="函数声明"></a>函数声明</h2><p>用户自定义函数，需要在主调函数中对被调函数做<code>声明</code>。其作用是把函数的具体信息(函数名、函数参数个数，参数类型等)通知给编译系统。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">int</span> <span class="title">add</span><span class="params">(<span class="keyword">int</span> x,<span class="keyword">int</span> y)</span></span>; <span class="comment">//函数声明 ，可以不带参数名</span></span><br><span class="line">	...</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">add</span><span class="params">(<span class="keyword">int</span> x,<span class="keyword">int</span> y)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">return</span> x+y;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<h2 id="函数的递归调用"><a href="#函数的递归调用" class="headerlink" title="函数的递归调用"></a>函数的递归调用</h2><ul>
<li><p>函数不可以嵌套定义，但可以嵌套调用。</p>
</li>
<li><p>当调用一个函数的过程中又出现直接或间接地调用该函数本身，称为函数的递归调用。</p>
</li>
<li><p>通过使用if语句来终止无止尽的递归。</p>
</li>
<li><p>一个递归的问题可以分为”回溯”和”递推”两部分。</p>
</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//使用递归的方法求n！</span></span><br><span class="line"><span class="comment">//当n=0,1时，n!=1; 当n&gt;1时，n!=n*(n-1)!</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">int</span> <span class="title">fac</span><span class="params">(<span class="keyword">int</span> n)</span></span>;  <span class="comment">//函数声明</span></span><br><span class="line">	<span class="keyword">int</span> n,y;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;input an integer number&quot;</span>);</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;n);</span><br><span class="line">	y=fac(n);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;%d!=%d\n&quot;</span>,n,y);</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">fac</span><span class="params">(<span class="keyword">int</span> n)</span></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> f;</span><br><span class="line">	<span class="keyword">if</span>(n&lt;<span class="number">0</span>)</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;n&lt;0,data error!&quot;</span>);</span><br><span class="line">	<span class="keyword">else</span> <span class="keyword">if</span>(n==<span class="number">0</span>||n==<span class="number">1</span>)</span><br><span class="line">		f=<span class="number">1</span>;</span><br><span class="line">	<span class="keyword">else</span></span><br><span class="line">		f=fac(n<span class="number">-1</span>)*n;  <span class="comment">//n&gt;1时，n!=n*(n-1)</span></span><br><span class="line">	<span class="keyword">return</span> f;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/*Hanoi(汉诺问题)</span></span><br><span class="line"><span class="comment">古代有一个梵塔，塔内有3个座A，B，C，开始时A座上有64个盘子，盘子大小不等，大的在下，小的在上。有一个老和尚想把这64个盘子从A座移到C座，但规定每次只能移动一个盘，且在移动过程中在3个座上始终保存大盘在下，小盘在上。在移动过程中可以利用B座。要求编程序输出移动盘子的过程。</span></span><br><span class="line"><span class="comment">解题思路：</span></span><br><span class="line"><span class="comment">①老和尚1命令第2个和尚将63个盘子从A移到B。</span></span><br><span class="line"><span class="comment">②自己将1一个盘子（最底下的、最大的盘子）从A移到C。</span></span><br><span class="line"><span class="comment">③再命令第2个和尚将63个盘子从B移到C。</span></span><br><span class="line"><span class="comment">第2个和尚依次递归。</span></span><br><span class="line"><span class="comment">例如先分析将A座上3个盘子移到C座：</span></span><br><span class="line"><span class="comment">①将A座上2个盘子移到B座（借助C）。 A-&gt;C,A-&gt;C,C-&gt;B</span></span><br><span class="line"><span class="comment">②将A座上1个盘子移到C座。		A-&gt;C</span></span><br><span class="line"><span class="comment">③将B座上2个盘子移到C座上（借助A）。B-&gt;A  B-&gt;C,A-&gt;C</span></span><br><span class="line"><span class="comment">分析可知：</span></span><br><span class="line"><span class="comment">移动n个盘子要经历(2^n-1)步，3个盘子要7步。</span></span><br><span class="line"><span class="comment">①将A座上n-1个盘子移到B座（借助C）。 A-&gt;C,A-&gt;C,C-&gt;B</span></span><br><span class="line"><span class="comment">②将A座上1个盘子移到C座。		A-&gt;C</span></span><br><span class="line"><span class="comment">③将B座上n-1个盘子移到C座上（借助A）。B-&gt;A  B-&gt;C,A-&gt;C</span></span><br><span class="line"><span class="comment">①③步都是n-1个盘子从一个座移到另一个座上。</span></span><br><span class="line"><span class="comment">因此，可以分解成两类操作：</span></span><br><span class="line"><span class="comment">（1）将n-1个盘子从一个座移到另一个座上(n&gt;1)。这就是大和尚让小和尚做的工作</span></span><br><span class="line"><span class="comment">（2）将1个盘子从一个座移到另一座上。这是大和尚自己做的工作。</span></span><br><span class="line"><span class="comment">*/</span></span><br><span class="line"><span class="comment">/*</span></span><br><span class="line"><span class="comment">编程思路：</span></span><br><span class="line"><span class="comment">分别用两个函数实现以上两类操作，用hanoi函数实现上面第1类操作（即模拟小和尚的认为），用move函数实现第2类操作（模拟大和尚的任务）。</span></span><br><span class="line"><span class="comment">函数调用hanoi(n,one,two,three)表示将n个盘子从”one“移到”three“座的过程（借助”two“）。</span></span><br><span class="line"><span class="comment">函数调用move(x,y)表示将1个盘子从x座移到y座的过程。x,y代表A,B,C座之一。</span></span><br><span class="line"><span class="comment">*/</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">void</span> <span class="title">hanoi</span><span class="params">(<span class="keyword">int</span> n,<span class="keyword">char</span> one,<span class="keyword">char</span> two,<span class="keyword">char</span> three)</span></span>; <span class="comment">//对hanoi函数的声明</span></span><br><span class="line">	<span class="keyword">int</span> m;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;input the number of diskes:&quot;</span>);</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;m);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;The step to move %d diskes:\n&quot;</span>,m);</span><br><span class="line">	hanoi(m,<span class="string">&#x27;A&#x27;</span>,<span class="string">&#x27;B&#x27;</span>,<span class="string">&#x27;C&#x27;</span>); </span><br><span class="line">&#125; </span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">hanoi</span><span class="params">(<span class="keyword">int</span> n,<span class="keyword">char</span> one,<span class="keyword">char</span> two,<span class="keyword">char</span> three)</span></span></span><br><span class="line"><span class="function"></span>&#123;  <span class="comment">//将n个盘从one座借助two座，移到three座</span></span><br><span class="line">	<span class="function"><span class="keyword">void</span> <span class="title">move</span><span class="params">(<span class="keyword">char</span> x,<span class="keyword">char</span> y)</span></span>;  <span class="comment">//对move函数的声明，因为主函数不需要调用，所以可以在函数内声明</span></span><br><span class="line">	<span class="keyword">if</span>(n==<span class="number">1</span>)</span><br><span class="line">		move(one,three); </span><br><span class="line">	<span class="keyword">else</span></span><br><span class="line">	&#123;</span><br><span class="line">		hanoi(n<span class="number">-1</span>,one,three,two);</span><br><span class="line">		move(one,three);</span><br><span class="line">		hanoi(n<span class="number">-1</span>,two,one,three);</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">move</span><span class="params">(<span class="keyword">char</span> x,<span class="keyword">char</span> y)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;%c-&gt;%c\n&quot;</span>,x,y);</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">/*</span></span><br><span class="line"><span class="comment">input the number of diskes:3</span></span><br><span class="line"><span class="comment">The step to move 3 diskes:</span></span><br><span class="line"><span class="comment">A-&gt;C</span></span><br><span class="line"><span class="comment">A-&gt;B</span></span><br><span class="line"><span class="comment">C-&gt;B</span></span><br><span class="line"><span class="comment">A-&gt;C</span></span><br><span class="line"><span class="comment">B-&gt;A</span></span><br><span class="line"><span class="comment">B-&gt;C</span></span><br><span class="line"><span class="comment">A-&gt;C</span></span><br><span class="line"><span class="comment">*/</span></span><br></pre></td></tr></table></figure>

<h2 id="数组作为函数参数"><a href="#数组作为函数参数" class="headerlink" title="数组作为函数参数"></a>数组作为函数参数</h2><ul>
<li><p>数组元素可以作为函数实参，不能用作形参。(因为形参是函数被调用时临时分配内存，不可能为单个数组元素分配存储单元，数组都是连续存放的）</p>
</li>
<li><p>数组名可以作为函数实参或者形参。注意，数组名做实参时，向形参传递的是数组元素<code>首地址</code>。</p>
</li>
<li><p>当形参数组名获得了实参数组的首地址后，它们共占同一存储单元，具有相同的值。</p>
</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//选择排序:对数组中10个整数由小到大排序 </span></span><br><span class="line"><span class="comment">//每一轮找出未经排序的数中最小的一个</span></span><br><span class="line"><span class="comment">//由于形参数组已经使用选择符排序了，形参数组改变实参数组也随之改变了</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">void</span> <span class="title">sort</span><span class="params">(<span class="keyword">int</span> <span class="built_in">array</span>[],<span class="keyword">int</span> n)</span></span>; <span class="comment">//函数声明</span></span><br><span class="line">	<span class="keyword">int</span> a[<span class="number">10</span>],i;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;enter array:\n&quot;</span>);</span><br><span class="line">	<span class="keyword">for</span>(i=<span class="number">0</span>;i&lt;<span class="number">10</span>;i++)</span><br><span class="line">		<span class="built_in">scanf</span>(<span class="string">&quot;%d&quot;</span>,&amp;a[i]);</span><br><span class="line">	sort(a,<span class="number">10</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;The sorted array:\n&quot;</span>);</span><br><span class="line">	<span class="keyword">for</span>(i=<span class="number">0</span>;i&lt;<span class="number">10</span>;i++)</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;%d\t&quot;</span>,a[i]);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;\n&quot;</span>); </span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125; </span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">sort</span><span class="params">(<span class="keyword">int</span> <span class="built_in">array</span>[],<span class="keyword">int</span> n)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> i,j,k,t;</span><br><span class="line">	<span class="keyword">for</span>(i=<span class="number">0</span>;i&lt;n<span class="number">-1</span>;i++)&#123;</span><br><span class="line">		k=i;</span><br><span class="line">		<span class="keyword">for</span>(j=i+<span class="number">1</span>;j&lt;n;j++)</span><br><span class="line">			<span class="keyword">if</span>(<span class="built_in">array</span>[j]&lt;<span class="built_in">array</span>[k])</span><br><span class="line">				k=j;</span><br><span class="line">				t=<span class="built_in">array</span>[k];</span><br><span class="line">				<span class="built_in">array</span>[k]=<span class="built_in">array</span>[i];</span><br><span class="line">				<span class="built_in">array</span>[i]=t;</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<h2 id="局部变量和全局变量"><a href="#局部变量和全局变量" class="headerlink" title="局部变量和全局变量"></a>局部变量和全局变量</h2><ul>
<li><p>在一个函数内定义的变量是<code>局部变量</code>，只在本函数范围内有效。</p>
</li>
<li><p>在函数外定义的变量是<code>全局变量</code>，可以为本文件中其他函数所共用。</p>
</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="keyword">int</span> a=<span class="number">3</span>,b=<span class="number">5</span>;  <span class="comment">//全局变量</span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">int</span> <span class="title">max</span><span class="params">(<span class="keyword">int</span> a,<span class="keyword">int</span> b)</span></span>; <span class="comment">//函数声明</span></span><br><span class="line">	<span class="keyword">int</span> a=<span class="number">8</span>;            	<span class="comment">//局部变量</span></span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;max=%d\n&quot;</span>,max(a,b));</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">max</span><span class="params">(<span class="keyword">int</span> a,<span class="keyword">int</span> b)</span></span></span><br><span class="line"><span class="function"></span>&#123;  <span class="comment">//形参a,b的作用范围</span></span><br><span class="line">	<span class="keyword">int</span> c;</span><br><span class="line">	c=a&gt;b?a:b;</span><br><span class="line">	<span class="keyword">return</span> c;</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">// 运行结果：max=8</span></span><br><span class="line">为什么结果为<span class="number">8</span>呢？</span><br><span class="line">因为全局变量a被局部变量a屏蔽了，相当于全局变量a在<span class="number">6</span>~<span class="number">8</span>行不存在，所以函数max是比较<span class="number">8</span>和<span class="number">5</span>的大小。</span><br></pre></td></tr></table></figure>
<blockquote>
<p>全局变量在程序的全部执行过程中都占用存储单元。</p>
</blockquote>
<h2 id="变量的存储方式和生存期"><a href="#变量的存储方式和生存期" class="headerlink" title="变量的存储方式和生存期"></a>变量的存储方式和生存期</h2><p>从变量的作用域来看，变量可以分<code>全局变量</code>和<code>局部变量</code>。<br>从变量生存期来看，变量的存储可以分<code>静态存储方式</code>和<code>动态存储方式</code>。</p>
<ul>
<li>静态存储方式：指在程序运行期间由系统分配固定的存储空间的方式。</li>
<li>动态存储方式：指在程序运行期间根据需要进行动态的分配存储空间的方式。</li>
</ul>
<p>内存中共用户使用的存储空间分3部分：<br>①程序区<br>②静态存储区<br>③动态存储区<br>数据分别存放在静态存储区和动态存储区中，全局变量全部存放在静态存储区中，在程序开始执行时给全局变量分配存储区，程序执行完毕后释放，在执行过程中占据固定的存储空间。<br>在动态存储区中存放以下数据：<br>①函数形式参数<br>②函数中没有用关键字static声明的变量，即自动变量<br>③函数调用时的现场保护和返回地址等</p>
<h2 id="存储类别"><a href="#存储类别" class="headerlink" title="存储类别"></a>存储类别</h2><p>每一个变量和函数都有两个属性：数据类型和数据的存储类别（如静态存储和动态存储）。<br>C的存储类别包括4种：自动的(auto)、静态的(static)、寄存器的(register)、外部的(extern)。</p>
<ul>
<li>自动变量auto<br>自动变量动态分配存储空间，属于动态存储类别，数据存储在动态存储区中，函数调用结束后即释放，函数中的形参和定义的局部变量都属于此类。</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">	<span class="function"><span class="keyword">int</span> <span class="title">f</span><span class="params">(<span class="keyword">int</span> a)</span></span></span><br><span class="line"><span class="function">	</span>&#123;</span><br><span class="line">	<span class="keyword">auto</span> <span class="keyword">int</span> b,c=<span class="number">3</span>;</span><br><span class="line">	&#125;</span><br><span class="line"><span class="comment">//其中a是形参，b和c是自动变量，对c赋初值3，执行完f函数后，自动释放a,b,c所占的内存单元</span></span><br></pre></td></tr></table></figure>
<blockquote>
<p>实际上关键字”auto“可以省略，不写auto则隐含指定为”自动存储类别“。</p>
</blockquote>
<ul>
<li><p>静态局部变量static<br>静态局部变量属于静态存储类别，在静态存储区内分配存储单元，在程序整个运行期间都不释放。</p>
<blockquote>
<p>对静态局部变量是在编译时赋初值的，即只赋值一次，以后每次调用函数时不用重新赋值而是保留上次函数调用结束时结束的值。</p>
</blockquote>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//输出1到5的阶乘值</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">int</span> <span class="title">fac</span><span class="params">(<span class="keyword">int</span> n)</span></span>;</span><br><span class="line">	<span class="keyword">int</span> i;</span><br><span class="line">	<span class="keyword">for</span>(i=<span class="number">0</span>;i&lt;=<span class="number">5</span>;i++)    <span class="comment">//先后5次调用fac函数</span></span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;%d!=%d\n&quot;</span>,i,fac(i));</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">fac</span><span class="params">(<span class="keyword">int</span> n)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">static</span> <span class="keyword">int</span> f=<span class="number">1</span>;  <span class="comment">//f保留了上次调用结束的值</span></span><br><span class="line">	f=f*n;  	<span class="comment">//上次的f值的基础上再乘以n</span></span><br><span class="line">	<span class="keyword">return</span> f;		<span class="comment">//返回值f是n!的值</span></span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">/*</span></span><br><span class="line"><span class="comment">1！=1</span></span><br><span class="line"><span class="comment">2！=2</span></span><br><span class="line"><span class="comment">3！=6</span></span><br><span class="line"><span class="comment">4！=24</span></span><br><span class="line"><span class="comment">5！=120</span></span><br><span class="line"><span class="comment">*/</span></span><br></pre></td></tr></table></figure>
</li>
<li><p>寄存器变量register<br>变量的值一般是存放在内存中的，当程序用到哪一个变量的值是，由控制器发出指令将内存中该变量的值送到运算器进行运算，如果需要存数，再从运算器将数据送到内存中。<br>如果有一些变量使用频繁，为提高效率，允许将局部变量的值放到<code>CPU中的寄存器</code>中，这种变量叫寄存器变量。</p>
<pre><code>  register int f;</code></pre>
</li>
</ul>
<h2 id="外部变量extern"><a href="#外部变量extern" class="headerlink" title="外部变量extern"></a>外部变量extern</h2><p>此类属于全局变量范围，全局变量作用域从<code>变量的定义处</code>开始，到本程序文件的末尾。并通过extern可以扩展变量的作用域。</p>
<ul>
<li>在一个文件内扩展外部变量的作用域<br>可以是把作用域扩展到<code>变量定义处之前</code>。</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio,h&gt;</span></span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">int</span> <span class="title">max</span><span class="params">()</span></span>;</span><br><span class="line">	<span class="keyword">extern</span> <span class="keyword">int</span> A,B,C;   <span class="comment">//扩展外部变量的作用域，可以省略数据类型</span></span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;请输入3个整数:&quot;</span>);</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%d%d%d&quot;</span>,&amp;A,&amp;B,&amp;C);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;最大值:%d\n&quot;</span>,max());</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="keyword">int</span> A,B,C;     <span class="comment">//定义外部变量</span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">max</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> m;</span><br><span class="line">	m=A&gt;B?A:B;</span><br><span class="line">	<span class="keyword">if</span>(C&gt;m)</span><br><span class="line">		m=C;</span><br><span class="line">	<span class="keyword">return</span> m;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<ul>
<li>将外部变量的作用域扩展到其他文件<br>如果一个程序包括两个文件，两个文件都需要用到同一个外部变量Num，则可以在任一个文件中<code>定义外部变量</code>Num，在另一个文件中用<code>extern对Num做外部声明</code>，即”extern Num“。</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//file1.c</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="keyword">int</span> A;    		<span class="comment">//定义外部变量</span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">int</span> <span class="title">power</span><span class="params">(<span class="keyword">int</span>)</span></span>;	<span class="comment">//函数声明</span></span><br><span class="line">	....</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//file2.c</span></span><br><span class="line"><span class="keyword">extern</span> A;   	<span class="comment">//作用域扩展</span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">power</span><span class="params">(<span class="keyword">int</span> n)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	...</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>


<ul>
<li>将外部变量的作用域限制在本文件中<br>static声明可以将外部变量只限于本文件引用。</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//file1.c</span></span><br><span class="line"><span class="keyword">static</span> <span class="keyword">int</span> A;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">...</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//file2.c</span></span><br><span class="line"><span class="keyword">extern</span> A;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">fun</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	...<span class="comment">//运行出错</span></span><br><span class="line">&#125;</span><br><span class="line"></span><br></pre></td></tr></table></figure>
<h2 id="内部函数和外部函数"><a href="#内部函数和外部函数" class="headerlink" title="内部函数和外部函数"></a>内部函数和外部函数</h2><ul>
<li><p>内部函数<br>如果一个函数只能被本文件内其他函数所调用，则称为<code>内部函数</code>（静态函数）。</p>
<pre><code>  static 类型名 函数名（形参名）
  static int fun(int a,intb);</code></pre>
</li>
<li><p>外部函数<br>如果定义函数时省略extern，则默认为外部函数。</p>
<pre><code>  extern int fun(int a,int b);</code></pre>
</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//分别定义3个函数用来输入字符串、删除字符、输出字符串。分别放在3个文件中，main函数在另一文件中，由它来调用以上3个函数。</span></span><br><span class="line"><span class="comment">//file.c</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span><span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="function"><span class="keyword">extern</span> <span class="keyword">void</span> <span class="title">enter_string</span><span class="params">(<span class="keyword">char</span> str[])</span></span>;    <span class="comment">//对函数的声明</span></span><br><span class="line">	<span class="function"><span class="keyword">extern</span> <span class="keyword">void</span> <span class="title">delete_string</span><span class="params">(<span class="keyword">char</span> str[],<span class="keyword">char</span> ch)</span></span>;</span><br><span class="line">	<span class="function"><span class="keyword">extern</span> <span class="keyword">void</span> <span class="title">print_string</span><span class="params">(<span class="keyword">char</span> str[])</span></span>;</span><br><span class="line">	<span class="keyword">char</span> c,str[<span class="number">80</span>];</span><br><span class="line">	enter_string(str);</span><br><span class="line">	<span class="built_in">scanf</span>(<span class="string">&quot;%c&quot;</span>,&amp;c);</span><br><span class="line">	delete_string(str,c);</span><br><span class="line">	printf_string(str);</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//file2.c</span></span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">enter_string</span><span class="params">(<span class="keyword">char</span> str[<span class="number">80</span>])</span>  <span class="comment">//定义外部函数</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	gets(str);</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//file3.c</span></span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">delete_string</span><span class="params">(<span class="keyword">char</span>[],<span class="keyword">char</span> ch)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="keyword">int</span> i,j;</span><br><span class="line">	<span class="keyword">for</span>(i=j=<span class="number">0</span>;str[i]!=<span class="string">&#x27;\0&#x27;</span>;i++)</span><br><span class="line">		<span class="keyword">if</span>(str[i]!=ch)</span><br><span class="line">			str[j++]=str[i];</span><br><span class="line">	str[j]=<span class="string">&#x27;\0&#x27;</span>;</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//file4.c</span></span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">print_string</span><span class="params">(<span class="keyword">char</span> str[])</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;%s\n&quot;</span>,str);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>


<blockquote>
<p>enter_string为函数原型，函数原型能够把函数的作用域扩展到定义该函数的文件之外（不需要extern),典型例子是#include指令的作用。</p>
</blockquote>
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class="toc-content"><ol class="toc"><li class="toc-item toc-level-1"><a class="toc-link" href="#%E5%87%BD%E6%95%B0"><span class="toc-number">1.</span> <span class="toc-text">函数</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#%E8%99%9A%E5%AE%9E%E7%BB%93%E5%90%88"><span class="toc-number">1.1.</span> <span class="toc-text">虚实结合</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E8%BF%94%E5%9B%9E%E5%80%BC"><span class="toc-number">1.2.</span> <span class="toc-text">返回值</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%87%BD%E6%95%B0%E5%A3%B0%E6%98%8E"><span class="toc-number">1.3.</span> <span class="toc-text">函数声明</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%87%BD%E6%95%B0%E7%9A%84%E9%80%92%E5%BD%92%E8%B0%83%E7%94%A8"><span class="toc-number">1.4.</span> <span class="toc-text">函数的递归调用</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E6%95%B0%E7%BB%84%E4%BD%9C%E4%B8%BA%E5%87%BD%E6%95%B0%E5%8F%82%E6%95%B0"><span class="toc-number">1.5.</span> <span class="toc-text">数组作为函数参数</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%B1%80%E9%83%A8%E5%8F%98%E9%87%8F%E5%92%8C%E5%85%A8%E5%B1%80%E5%8F%98%E9%87%8F"><span class="toc-number">1.6.</span> <span class="toc-text">局部变量和全局变量</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%8F%98%E9%87%8F%E7%9A%84%E5%AD%98%E5%82%A8%E6%96%B9%E5%BC%8F%E5%92%8C%E7%94%9F%E5%AD%98%E6%9C%9F"><span class="toc-number">1.7.</span> <span class="toc-text">变量的存储方式和生存期</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%AD%98%E5%82%A8%E7%B1%BB%E5%88%AB"><span class="toc-number">1.8.</span> <span class="toc-text">存储类别</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%A4%96%E9%83%A8%E5%8F%98%E9%87%8Fextern"><span class="toc-number">1.9.</span> <span class="toc-text">外部变量extern</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%86%85%E9%83%A8%E5%87%BD%E6%95%B0%E5%92%8C%E5%A4%96%E9%83%A8%E5%87%BD%E6%95%B0"><span class="toc-number">1.10.</span> <span class="toc-text">内部函数和外部函数</span></a></li></ol></li></ol></div></div><div class="card-widget card-recent-post"><div class="item-headline"><i class="fas fa-history"></i><span>最新文章</span></div><div class="aside-list"><div class="aside-list-item"><a class="thumbnail" href="/page/project01.html" title="前端实例🥳响应式网站首页"><img src="https://cdn.jsdelivr.net/gh/xiaoliblog/image@c19917500ab083c77c7613263ba7ee74d5a08ae6/2021/04/30/469f30b141d73fa0fc4c962662d5813f.png" onerror="this.onerror=null;this.src='https://cdn.jsdelivr.net/gh/lzyblog/image@main/2020/11/19/bd16b394f7359083b1f6072a67e3f968.png'" alt="前端实例🥳响应式网站首页"/></a><div class="content"><a class="title" href="/page/project01.html" title="前端实例🥳响应式网站首页">前端实例🥳响应式网站首页</a><time datetime="2021-04-30T11:50:53.094Z" 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})()</script></div><script defer src="//lib.baomitu.com/jquery/3.5.1/jquery.min.js"></script><script defer src="https://myhkw.cn/api/player/160561664166" id="myhk" key="160561664166" m="1"></script><div><canvas id="snow" style="position:fixed;top:0;left:0;width:100%;height:100%;z-index:99999;pointer-events:none"></canvas></div><script>const notMobile = (!(navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i)));</script><scrip async type="text/javascript" src="https://cdn.jsdelivr.net/gh/Candinya/Kratos-Rebirth@latest/source/js/snow.min.js"></scrip><scrip defer src="https://cdn.jsdelivr.net/npm/hexo-theme-volantis@latest/source/js/issues.min.js"></scrip><script async data-pjax src="//busuanzi.ibruce.info/busuanzi/2.3/busuanzi.pure.mini.js"></script><script>var gitcalendar = new Vue({
  el: '#gitcalendar',
  data: {
    simplemode: true, 
    user: 'xiaoliblog',
    fixed: 'fixed',
    px: 'px',
    x: '',
    y: '',
    span1: '',
    span2: '',
    month: ['一月', '二月', '三月', '四月', '五月', '六月', '七月', '八月', '九月', '十月', '十一月', '十二月'],
    monthchange: [],
    oneyearbeforeday: '',
    thisday: '',
    amonthago: '',
    aweekago: '',
    weekdatacore: 0,
    datacore: 0,
    total: 0,
    datadate: '',
    data: [],
    positionplusdata: [],
    firstweek: [],
    lastweek: [],
    beforeweek: [],
    thisweekdatacore: 0,
    mounthbeforeday: 0,
    mounthfirstindex: 0,
    crispedges: 'crispedges',
    thisdayindex: 0,
    amonthagoindex: 0,
    amonthagoweek: [],
    firstdate: [],
    first2date: [],
    montharrbefore: [],
    monthindex: 0,
    color: ['#ebedf0', '#f1f8ff', '#dbedff', '#c8e1ff', '#79b8ff', '#2188ff', '#0366d6', '#005cc5', '#044289', '#032f62', '#05264c']
  },
  methods: {
    selectStyle(data, event) {
      document.querySelector('.angle-wrapper').style.display = 'block'
      this.span1 = data.date;
      this.span2 = data.count;
      this.x = event.clientX - 100;
      this.y = event.clientY - 60
    },
    outStyle() {
      document.querySelector('.angle-wrapper').style.display = 'none'
    },
    thiscolor(x) {
      if (x === 0) {
        let i = parseInt(x / 2);
        return this.color[0]
      } else if (x < 2) {
        return this.color[1]
      } else if (x < 20) {
        let i = parseInt(x / 2);
        return this.color[i]
      } else {
        return this.color[9]
      }
    },
  }
});
var apiurl = 'python-github-calendar-api-ruby.vercel.app' ? 'https://python-github-calendar-api-ruby.vercel.app/api?' : 'https://githubapi.ryanchristian.dev/user/'
var githubapiurl = apiurl + gitcalendar.user;
//canvas绘图
function responsiveChart() {
  let c = document.getElementById("gitcanvas");
  if (c) {
    let cmessage = document.getElementById("gitmessage");
    let ctx = c.getContext("2d");
    c.width = document.getElementById("gitcalendarcanvasbox").offsetWidth;
    let linemaxwitdh = 0.96 * c.width / gitcalendar.data.length;
    c.height = 9 * linemaxwitdh;
    let lineminwitdh = 0.8 * linemaxwitdh;
    let setposition = {
      x: 0.02 * c.width,
      y: 0.025 * c.width
    };
    for (let week in gitcalendar.data) {
      weekdata = gitcalendar.data[week];
      for (let day in weekdata) {
        let dataitem = {
          date: "",
          count: "",
          x: 0,
          y: 0
        };
        gitcalendar.positionplusdata.push(dataitem);
        ctx.fillStyle = gitcalendar.thiscolor(weekdata[day].count);
        setposition.y = Math.round(setposition.y * 100) / 100;
        dataitem.date = weekdata[day].date;
        dataitem.count = weekdata[day].count;
        dataitem.x = setposition.x;
        dataitem.y = setposition.y;
        ctx.fillRect(setposition.x, setposition.y, lineminwitdh, lineminwitdh);
        setposition.y = setposition.y + linemaxwitdh
      };
      setposition.y = 0.025 * c.width;
      setposition.x = setposition.x + linemaxwitdh
    };
    ctx.font = "600  Arial";
    ctx.fillStyle = '#aaa';
    ctx.fillText("日", 0, 1.9 * linemaxwitdh);
    ctx.fillText("二", 0, 3.9 * linemaxwitdh);
    ctx.fillText("四", 0, 5.9 * linemaxwitdh);
    ctx.fillText("六", 0, 7.9 * linemaxwitdh);
    let monthindexlist = c.width / 24;
    for (let index in gitcalendar.monthchange) {
      ctx.fillText(gitcalendar.monthchange[index], monthindexlist, 0.7 * linemaxwitdh);
      monthindexlist = monthindexlist + c.width / 12
    };
    cmessage.onmousemove = function(event) {
      document.querySelector('.angle-wrapper').style.display = 'none'
    };
    c.onmousemove = function(event) {
      document.querySelector('.angle-wrapper').style.display = 'none'
      getMousePos(c, event);
    };

    function getMousePos(canvas, event) {
      var rect = canvas.getBoundingClientRect();
      var x = event.clientX - rect.left * (canvas.width / rect.width);
      var y = event.clientY - rect.top * (canvas.height / rect.height);
      //console.log("x:"+x+",y:"+y);
      for (let item of gitcalendar.positionplusdata) {
        let lenthx = x - item.x;
        let lenthy = y - item.y;
        //console.log(lenthx,lenthy);
        if (0 < lenthx && lenthx < lineminwitdh) {
          if (0 < lenthy && lenthy < lineminwitdh) {
            //console.log(item.date,item.count)
            document.querySelector('.angle-wrapper').style.display = 'block'
            gitcalendar.span1 = item.date;
            gitcalendar.span2 = item.count;
            gitcalendar.x = event.clientX - 100;
            gitcalendar.y = event.clientY - 60
          }
        }
        //if(0< x - item.x <lineminwitdh&&0< y - item.y <lineminwitdh){
        //console.log(item.count,item.date);
        //}
      }
    }
  }
}
//数据统计算法
function addlastmonth() {
  if (gitcalendar.thisdayindex === 0) {
    thisweekcore(52);
    thisweekcore(51);
    thisweekcore(50);
    thisweekcore(49);
    thisweekcore(48);
    gitcalendar.thisweekdatacore += gitcalendar.firstdate[6].count;
    gitcalendar.amonthago = gitcalendar.firstdate[6].date
  } else {
    thisweekcore(52);
    thisweekcore(51);
    thisweekcore(50);
    thisweekcore(49);
    thisweek2core();
    gitcalendar.amonthago = gitcalendar.first2date[gitcalendar.thisdayindex - 1].date
  }
};

function thisweek2core() {
  for (let i = gitcalendar.thisdayindex - 1; i < gitcalendar.first2date.length; i++) {
    gitcalendar.thisweekdatacore += gitcalendar.first2date[i].count
  }
};

function thisweekcore(index) {
  for (let item of gitcalendar.data[index]) {
    gitcalendar.thisweekdatacore += item.count
  }
};

function addlastweek() {
  for (let item of gitcalendar.lastweek) {
    gitcalendar.weekdatacore += item.count
  }
};

function addbeforeweek() {
  for (let i = gitcalendar.thisdayindex; i < gitcalendar.beforeweek.length; i++) {
    gitcalendar.weekdatacore += gitcalendar.beforeweek[i].count
  }
};

function addweek(data) {
  if (gitcalendar.thisdayindex === 6) {
    gitcalendar.aweekago = gitcalendar.lastweek[0].date;
    addlastweek()
  } else {
    lastweek = data.contributions[51];
    gitcalendar.aweekago = lastweek[gitcalendar.thisdayindex + 1].date;
    addlastweek();
    addbeforeweek()
  }
}

fetch(githubapiurl)
  .then(data => data.json())
  .then(data => {
    gitcalendar.data = data.contributions;
    gitcalendar.total = data.total;
    gitcalendar.first2date = gitcalendar.data[48];
    gitcalendar.firstdate = gitcalendar.data[47];
    gitcalendar.firstweek = data.contributions[0];
    gitcalendar.lastweek = data.contributions[52];
    gitcalendar.beforeweek = data.contributions[51];
    gitcalendar.thisdayindex = gitcalendar.lastweek.length - 1;
    gitcalendar.thisday = gitcalendar.lastweek[gitcalendar.thisdayindex].date;
    gitcalendar.oneyearbeforeday = gitcalendar.firstweek[0].date;
    gitcalendar.monthindex = gitcalendar.thisday.substring(5, 7) * 1;
    gitcalendar.montharrbefore = gitcalendar.month.splice(gitcalendar.monthindex, 12 - gitcalendar.monthindex);
    gitcalendar.monthchange = gitcalendar.montharrbefore.concat(gitcalendar.month);
    addweek(data);
    addlastmonth();
    responsiveChart();
  })
  .catch(function(error) {
    console.log(error);
  });

//手机版更换为svg绘制
if (document.getElementById("gitcalendarcanvasbox").offsetWidth < 500) {
  gitcalendar.simplemode = false
}

//当改变窗口大小时重新绘制canvas
window.onresize = function() {
  if (gitcalendar.simplemode) responsiveChart()
}

//解决滚动滑轮时出现的标签显示
window.onscroll = function() {
  if (document.querySelector('.angle-wrapper')) {
    document.querySelector('.angle-wrapper').style.display = 'none'
  }
};</script></div><script src="/live2dw/lib/L2Dwidget.min.js?094cbace49a39548bed64abff5988b05"></script><script>L2Dwidget.init({"pluginRootPath":"live2dw/","pluginJsPath":"lib/","pluginModelPath":"assets/","tagMode":false,"log":false,"model":{"jsonPath":"/live2dw/assets/hijiki.model.json"},"display":{"position":"right","width":150,"height":300},"mobile":{"show":true},"react":{"opacity":0.7}});</script></body></html>